$3250 for a 100K Insight isn't bad! If you purchase, keep in mind some negotiation points if any of them apply:
- Oil leak - as Ecky said, avoid those
- Transmission downshift grinding
- CEL - usually catalytic converters or O2 sensors if not an IMA issue. Bring a tester and check for yourself
- IMA light
- Missing underbody panels
- Rust on brake lines, etc.
- Evidence of damage, etc., as with any car
If you get the car and later on end up needing to replace the IMA battery, drive without it for a few days to see if you can handle it without the battery. I did that when I was diagnosing an IMA light issue (turned out to be ground straps - an easy $15 fix). Fuel economy was literally the same without the battery -- and in some cases better since I could EOC to stops rather than regen brake -- and driveability really wasn't that much different to me. It's just a matter of disconnecting the BCM and turning off the battery to temporarily run it gasoline only.